Rework Kfont to store glyph top as offset from top of text row

This fixes having leftover pixels on screen bottom when scrolling the
console up.

.gitignore

@@ -1,3 +1,4 @@
 .rscons*
 /x86_64-elf-gcc/
 /build/
+/qemu/

README.md

@@ -17,6 +17,8 @@ the build command.
 
 # Running HOS
 
+HOS can run on a physical machine, in VirtualBox, or in QEMU.
+
 ## Physical Machine
 
 To install HOS to an EFI partition, follow these steps:
@@ -69,3 +71,10 @@ To create a VM in VirtualBox:
 14. Under System, check the Enable EFI checkbox.
 15. Under Storage, add a hard disk and browse to select the HOS.vmdk file.
 16. To run HOS, either start the VM through VirtualBox or with "./rscons run-vb".
+
+## QEMU
+
+Make sure QEMU is installed (possibly the `qemu-desktop` package). Then:
+
+1. Build HOS ("./rscons").
+2. Run `./rscons run` to run HOS in QEMU.

Rsconscript

@@ -26,7 +26,7 @@ MB = 1024 * 1024
 
 class HulkBinObj < Builder
   def run(options)
-    FileUtils.mkdir_p(File.dirname(@target))
+    @cache.mkdir_p(File.dirname(@target))
     File.write(@target, <<EOF)
 .section ".rodata"
 .balign 4096
@@ -162,6 +162,10 @@ hello_env = env "hello", use: %w[ldc2 x86_64-w64-mingw32-gcc] do |env|
   env.add_builder(CheckThreadLocal)
   env.add_builder(HulkBinObj)
   env["sources"] = glob("src/hello/**/*.d")
+  env["sources"] += %w[
+    src/hulk/serial.d
+    src/hulk/writef.d
+  ]
   env["sources"] += glob("uefi-d/source/**/*.d")
   env.HulkBinObj("^/hulk_bin.S", hulk_env.expand("^/hulk.bin"))
   env.Object("^/hulk_bin.o", "^/hulk_bin.S")
@@ -183,11 +187,22 @@ hello_env = env "hello", use: %w[ldc2 x86_64-w64-mingw32-gcc] do |env|
 end
 
 task "run", desc: "Run HOS in QEMU" do
-  Dir.mktmpdir do |tmpdir|
+  FileUtils.rm_rf("qemu")
+  FileUtils.mkdir_p("qemu")
   img = hello_env.expand("^/HOS.img")
-    FileUtils.cp(img, tmpdir)
-    sh %W[qemu-system-x86_64 -cpu max -bios OVMF.fd -drive file=#{tmpdir}/HOS.img,format=raw -device qemu-xhci -device usb-tablet]
+  FileUtils.cp(img, "qemu")
+  ovmf = "OVMF.fd"
+  if File.exist?("/usr/share/edk2/x64/OVMF.fd")
+    ovmf = "/usr/share/edk2/x64/OVMF.fd"
   end
+  sh %W[
+    qemu-system-x86_64
+    -cpu max
+    -serial file:qemu/serial.out
+    -bios #{ovmf}
+    -drive file=qemu/HOS.img,format=raw
+    -device qemu-xhci
+    -device usb-tablet]
 end
 
 # See README.md for how to set up VirtualBox for HOS.

src/fontgen/fontgen.c

@@ -1,5 +1,6 @@
 #include <stdlib.h>
 #include <stdint.h>
+#include <stdbool.h>
 #include <ft2build.h>
 #include <stdio.h>
 #include FT_FREETYPE_H
@@ -86,35 +87,43 @@ static void generate_bytes(FILE * file, const uint8_t * bytes, int count)
     }
 }
 
-static void generate(const char * d_file_name)
+static bool generate(const char * d_file_name)
 {
     FILE * fh = fopen(d_file_name, "wb");
     fprintf(fh, "module hulk.kfont;\n");
     fprintf(fh, "struct CharInfo {\n");
-    fprintf(fh, "    uint width;\n");
-    fprintf(fh, "    uint height;\n");
-    fprintf(fh, "    int top;\n");
-    fprintf(fh, "    int left;\n");
+    fprintf(fh, "    /** Glyph bitmap width. */\n");
+    fprintf(fh, "    ubyte width;\n");
+    fprintf(fh, "    /** Glyph bitmap height. */\n");
+    fprintf(fh, "    ubyte height;\n");
+    fprintf(fh, "    /** Glyph bitmap top offset (descent from top of text row). */\n");
+    fprintf(fh, "    ubyte top;\n");
+    fprintf(fh, "    /** Glyph bitmap left offset. */\n");
+    fprintf(fh, "    ubyte left;\n");
+    fprintf(fh, "    /** Glyph bitmap. */\n");
     fprintf(fh, "    const ubyte[] bitmap;\n");
     fprintf(fh, "};\n");
     fprintf(fh, "struct FontInfo {\n");
-    fprintf(fh, "    uint line_height;\n");
-    fprintf(fh, "    uint advance;\n");
-    fprintf(fh, "    int baseline_offset;\n");
+    fprintf(fh, "    /** Font line height. */\n");
+    fprintf(fh, "    ubyte line_height;\n");
+    fprintf(fh, "    /** Font advance. */\n");
+    fprintf(fh, "    ubyte advance;\n");
+    fprintf(fh, "    /** Characters. */\n");
     fprintf(fh, "    const CharInfo[] chars;\n");
     fprintf(fh, "};\n");
-    fprintf(fh, "__gshared const FontInfo kfont = {\n");
+    fprintf(fh, "/** Kernel font data. */\n");
+    fprintf(fh, "__gshared const FontInfo Kfont = {\n");
     fprintf(fh, "    %du,\n", line_height);
     fprintf(fh, "    %du,\n", max_advance);
-    fprintf(fh, "    %d,\n", baseline_offset);
     fprintf(fh, "    [\n");
     for (int i = 0; i < N_CHARS; i++)
     {
+        fprintf(fh, "        /* %d */", i);
         fprintf(fh, "        CharInfo(\n");
-        fprintf(fh, "            %du,\n", char_infos[i].width);
-        fprintf(fh, "            %du,\n", char_infos[i].height);
-        fprintf(fh, "            %d,\n", char_infos[i].top);
-        fprintf(fh, "            %d,\n", char_infos[i].left);
+        fprintf(fh, "            %du /* width */,\n", char_infos[i].width);
+        fprintf(fh, "            %du /* height */,\n", char_infos[i].height);
+        fprintf(fh, "            %du /* top */,\n", char_infos[i].top);
+        fprintf(fh, "            %du /* left */,\n", char_infos[i].left);
         if (char_infos[i].width > 0)
         {
             fprintf(fh, "            [\n");
@@ -130,6 +139,7 @@ static void generate(const char * d_file_name)
     fprintf(fh, "    ],\n");
     fprintf(fh, "};\n");
     fclose(fh);
+    return true;
 }
 
 int main(int argc, char * argv[])
@@ -167,7 +177,59 @@ int main(int argc, char * argv[])
     line_height = round_up_26_6(face->size->metrics.height);
     baseline_offset = (line_height - (max_top - min_bottom)) / 2 - min_bottom;
 
-    generate(out_file);
+    if ((line_height < 1) || (line_height > 0xFF))
+    {
+        fprintf(stderr, "Error: invalid line_height %d\n", line_height);
+        return false;
+    }
+    if ((max_advance < 1) || (max_advance > 0xFF))
+    {
+        fprintf(stderr, "Error: invalid max_advance %d\n", max_advance);
+        return false;
+    }
+
+    for (int i = 0; i < N_CHARS; i++)
+    {
+        if ((char_infos[i].width < 0) || (char_infos[i].width > max_advance))
+        {
+            fprintf(stderr, "Error: invalid character %d width: %d\n", i, char_infos[i].width);
+            return false;
+        }
+        if ((char_infos[i].height < 0) || (char_infos[i].height > line_height))
+        {
+            fprintf(stderr, "Error: invalid character %d height: %d\n", i, char_infos[i].height);
+            return false;
+        }
+        if ((char_infos[i].left < 0) || (char_infos[i].left >= max_advance))
+        {
+            fprintf(stderr, "Error: invalid character %d left: %d\n", i, char_infos[i].left);
+            return false;
+        }
+        /* Adjust character top to be index downward from top of font box. */
+        char_infos[i].top = line_height - baseline_offset - char_infos[i].top;
+        if ((char_infos[i].top < 0) || (char_infos[i].top >= line_height))
+        {
+            fprintf(stderr, "Error: invalid character %d top: %d\n", i, char_infos[i].top);
+            return false;
+        }
+        if ((char_infos[i].left + char_infos[i].width) > max_advance)
+        {
+            fprintf(stderr, "Error: character %d left (%d) + width (%d) > advance (%d)\n",
+                    i, char_infos[i].left, char_infos[i].width, max_advance);
+            return false;
+        }
+        if ((char_infos[i].top + char_infos[i].height) > line_height)
+        {
+            fprintf(stderr, "Error: character %d top (%d) + height (%d) > line height (%d)\n",
+                    i, char_infos[i].top, char_infos[i].height, line_height);
+            return false;
+        }
+    }
+
+    if (!generate(out_file))
+    {
+        return 1;
+    }
 
     return 0;
 }

src/hello/console.d

@@ -6,155 +6,62 @@ module hello.console;
 import uefi;
 import hello.hello;
 import core.stdc.stdarg;
+import hulk.writef;
 
-struct console
+struct Console
 {
     /**
-     * Format a hexadecimal value to a string.
+     * Write a character to the console.
      *
-     * @param s String buffer.
-     * @param v Value to format.
-     * @param ptr If true, always output all 16 digits, and separate the upper and
-     *   lower halves with an underscore.
+     * @param ch Character to write.
      */
-    private static size_t format_hex(CHAR16 * s, ulong v, bool ptr)
+    public static void write(ubyte ch)
     {
-        string hex_chars = "0123456789ABCDEF";
-        bool print = ptr;
-        size_t si = 0u;
-        for (size_t i = 0u; i < 16u; i++)
+        if (ch == '\n')
         {
-            if (ptr && (i == 8u))
-            {
-                s[si++] = '_';
+            write('\r');
         }
-            ulong n = (v >> (60u - 4u * i)) & 0xFu;
-            if (n != 0u)
-            {
-                print = true;
-            }
-            if (print || (i == 15u))
-            {
-                s[si++] = hex_chars[n];
-            }
-        }
-        return si;
-    }
-
-    /**
-     * Format a decimal value to a string.
-     *
-     * @param s String buffer.
-     * @param v Value to format.
-     */
-    private static size_t format_dec(CHAR16 * s, ulong v)
-    {
-        string dec_chars = "0123456789";
-        bool print;
-        char[20] buf;
-        size_t buf_i;
-        while ((buf_i == 0u) || (v != 0u))
-        {
-            ulong n = v % 10u;
-            buf[buf_i++] = dec_chars[n];
-            v /= 10u;
-        }
-        for (size_t si = 0u; si < buf_i; si++)
-        {
-            s[si] = buf[buf_i - si - 1u];
-        }
-        return buf_i;
-    }
-
-    /**
-     * Write a string to the console.
-     *
-     * @param s Format string.
-     * @param args Variable arguments structure.
-     */
-    public static void write(string s, va_list args)
-    {
-        __gshared static CHAR16[256] s16;
-        size_t i = 0u;
-        bool escape = false;
-        foreach (char c; s)
-        {
-            if (escape)
-            {
-                if (c == '%')
-                {
-                    s16[i++] = '%';
-                }
-                else if (c == 'x')
-                {
-                    ulong v;
-                    va_arg(args, v);
-                    i += format_hex(&s16[i], v, false);
-                }
-                else if (c == 'p')
-                {
-                    ulong v;
-                    va_arg(args, v);
-                    i += format_hex(&s16[i], v, true);
-                }
-                else if (c == 'S')
-                {
-                    const(CHAR16) * s2;
-                    va_arg(args, s2);
-                    for (size_t s2_i = 0u; s2[s2_i] != 0; s2_i++)
-                    {
-                        s16[i++] = s2[s2_i];
-                    }
-                }
-                else if (c == 'u')
-                {
-                    ulong v;
-                    va_arg(args, v);
-                    i += format_dec(&s16[i], v);
-                }
-                else
-                {
-                    s16[i++] = c;
-                }
-                escape = false;
-            }
-            else if (c == '%')
-            {
-                escape = true;
-            }
-            else
-            {
-                s16[i++] = c;
-            }
-        }
-        s16[i++] = 0u;
+        CHAR16[2] s16 = [ch, 0];
         st.ConOut.OutputString(st.ConOut, &s16[0]);
     }
 
     /**
-     * Write a string to the console.
+     * Write a formatted string to the console.
+     *
+     * @param s Format string.
+     * @param args Variable arguments structure.
+     */
+    public static void writef(string s, va_list args)
+    {
+        hulk.writef.writef(s, args, function void(ubyte ch) {
+                    Console.write(ch);
+                });
+    }
+
+    /**
+     * Write a formatted string to the console.
      *
      * @param s Format string.
      */
-    public static extern (C) void write(string s, ...)
+    public static extern (C) void writef(string s, ...)
     {
         va_list args;
         va_start(args, s);
-        write(s, args);
+        writef(s, args);
         va_end(args);
     }
 
     /**
-     * Write a string to the console.
+     * Write a formatted string and newline to the console.
      *
      * @param s Format string.
      */
-    public static extern (C) void writeln(string s, ...)
+    public static extern (C) void writefln(string s, ...)
     {
         va_list args;
         va_start(args, s);
-        write(s, args);
-        write("\r\n", args);
+        writef(s, args);
+        writef("\n", args);
         va_end(args);
     }
 
@@ -163,7 +70,7 @@ struct console
      */
     public static void wait_key()
     {
-        writeln("Press any key...");
+        writefln("Press any key...");
         st.ConIn.Reset(st.ConIn, FALSE);
         EFI_INPUT_KEY key;
         while (st.ConIn.ReadKeyStroke(st.ConIn, &key) == EFI_NOT_READY)

src/hello/hello.d

@@ -11,6 +11,7 @@ import hulk.pagetable;
 import hulk.cpu;
 import hulk.memory;
 import ldc.llvmasm;
+import hulk.serial;
 
 __gshared EFI_SYSTEM_TABLE * st;
 /** HULK binary start address, 4KB-aligned. */
@@ -93,7 +94,7 @@ private bool set_graphics_mode()
             &gop_guid, null, &buffer_size, handles);
     if (status != EFI_SUCCESS)
     {
-        console.writeln("LocateHandle: error %x", status);
+        Console.writefln("LocateHandle: error %x", status);
         return false;
     }
     EFI_HANDLE gop_handle = handles[0];
@@ -102,12 +103,12 @@ private bool set_graphics_mode()
             &gop_guid, &gop_interface);
     if (status != EFI_SUCCESS)
     {
-        console.writeln("HandleProtocol: error %x", status);
+        Console.writefln("HandleProtocol: error %x", status);
         return false;
     }
     if (gop_interface == null)
     {
-        console.writeln("null interface from HandleProtocol");
+        Console.writefln("null interface from HandleProtocol");
         return false;
     }
     EFI_GRAPHICS_OUTPUT_PROTOCOL * gop = cast(EFI_GRAPHICS_OUTPUT_PROTOCOL *)gop_interface;
@@ -129,7 +130,7 @@ private bool set_graphics_mode()
     }
     if ((status = gop.SetMode(gop, best_mode_number)) != EFI_SUCCESS)
     {
-        console.writeln("SetMode: Error %x\n", status);
+        Console.writefln("SetMode: Error %x\n", status);
         return false;
     }
     bootinfo().fb.buffer = cast(uint *)gop.Mode.FrameBufferBase;
@@ -174,7 +175,7 @@ private void get_memory_map(ulong * physical_address_limit, UINTN * memory_map_k
             &descriptor_version);
     if (status != EFI_SUCCESS)
     {
-        console.writeln("GetMemoryMap: Error %x", status);
+        Console.writefln("GetMemoryMap: Error %x", status);
         for (;;) {}
     }
     size_t n_entries = memory_map_size / descriptor_size;
@@ -187,7 +188,7 @@ private void get_memory_map(ulong * physical_address_limit, UINTN * memory_map_k
     {
         if (count > bootinfo().memory_map.length)
         {
-            console.writeln("Memory map too large");
+            Console.writefln("Memory map too large");
             for (;;) {}
         }
         EFI_MEMORY_DESCRIPTOR * descriptor = cast(EFI_MEMORY_DESCRIPTOR *)&scratch_base[count * descriptor_size];
@@ -205,6 +206,7 @@ private void get_memory_map(ulong * physical_address_limit, UINTN * memory_map_k
         }
         if (descriptor.Type >= efi_to_hulk_memory_map_type.length)
         {
+            Serial.writefln("Unexpected descriptor type %u", descriptor.Type);
             continue;
         }
         bootinfo().memory_map[count].base = descriptor.PhysicalStart;
@@ -217,6 +219,9 @@ private void get_memory_map(ulong * physical_address_limit, UINTN * memory_map_k
             bootinfo().bss_phys = bootinfo().memory_map[count].base;
             bootinfo().memory_map[count].base += hulk_bss_size();
             bootinfo().memory_map[count].size -= hulk_bss_size();
+            Serial.writefln("Locating HULK BSS at %x:%x",
+                    bootinfo().bss_phys,
+                    bootinfo().bss_phys + hulk_bss_size() - 1u);
             found_bss = true;
         }
         if ((!found_stack) &&
@@ -226,6 +231,9 @@ private void get_memory_map(ulong * physical_address_limit, UINTN * memory_map_k
             bootinfo().stack_phys = bootinfo().memory_map[count].base;
             bootinfo().memory_map[count].base += hulk_stack_size();
             bootinfo().memory_map[count].size -= hulk_stack_size();
+            Serial.writefln("Locating HULK stack at %x:%x",
+                    bootinfo().stack_phys,
+                    bootinfo().stack_phys + hulk_stack_size() - 1u);
             found_stack = true;
         }
         if ((!found_fb_buffer1) &&
@@ -235,8 +243,15 @@ private void get_memory_map(ulong * physical_address_limit, UINTN * memory_map_k
             bootinfo().fb_buffer1_phys = bootinfo().memory_map[count].base;
             bootinfo().memory_map[count].base += fb_size;
             bootinfo().memory_map[count].size -= fb_size;
+            Serial.writefln("Locating HULK FB1 at %x:%x",
+                    bootinfo().fb_buffer1_phys,
+                    bootinfo().fb_buffer1_phys + fb_size - 1u);
             found_fb_buffer1 = true;
         }
+        Serial.writefln("Memory range %x:%x (%u)",
+                bootinfo().memory_map[count].base,
+                bootinfo().memory_map[count].base + bootinfo().memory_map[count].size - 1u,
+                bootinfo().memory_map[count].type);
     }
     bootinfo().memory_map_count = count;
     if ((!found_bss) || (!found_stack) || (!found_fb_buffer1))
@@ -511,21 +526,21 @@ extern (C) EFI_STATUS efi_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE * st)
 {
     .st = st;
 
-    console.clear();
+    Console.clear();
 
-    console.writeln("Welcome to HELLO, HOS EFI Lightweight LOader, v0.1.0");
-    console.writeln("Firmware vendor: '%S', version: 0x%x", st.FirmwareVendor, st.FirmwareVendor);
+    Console.writefln("Welcome to HELLO, HOS EFI Lightweight LOader, v0.1.0");
+    Console.writefln("Firmware vendor: '%S', version: 0x%x", st.FirmwareVendor, st.FirmwareVendor);
 
     if (!find_acpi_xsdt())
     {
-        console.writeln("Error: Could not locate ACPI XSDT");
-        console.wait_key();
+        Console.writefln("Error: Could not locate ACPI XSDT");
+        Console.wait_key();
         return EFI_SUCCESS;
     }
 
     if (!set_graphics_mode())
     {
-        console.wait_key();
+        Console.wait_key();
         return EFI_SUCCESS;
     }
 
@@ -544,8 +559,8 @@ extern (C) EFI_STATUS efi_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE * st)
         {
             break;
         }
-        console.writeln("ExitBootServices: Error %x", status);
-        console.wait_key();
+        Console.writefln("ExitBootServices: Error %x", status);
+        Console.wait_key();
         return EFI_SUCCESS;
     }
 

src/hulk/acpi.d

@@ -7,12 +7,12 @@ import hulk.hurl;
 import hulk.klog;
 import hulk.memory;
 
-struct acpi
+struct Acpi
 {
     enum uint APIC_SIGNATURE = 0x43495041u;
     enum uint XSDT_SIGNATURE = 0x54445358u;
 
-    static struct XsdtHeader
+    static align(4) struct XsdtHeader
     {
         uint signature;
         uint length;
@@ -28,8 +28,8 @@ struct acpi
     static struct Xsdt
     {
         XsdtHeader header;
-        uint _pad;
-        ulong[0] tables;
+        /* Table pointers are not ulong-aligned! They begin at offset 36. */
+        align(4) ulong[1] tables;
     }
 
     static struct MadtHeader
@@ -58,21 +58,27 @@ struct acpi
     public static void initialize(ulong acpi_xsdt_phys)
     {
         /* Map the XSDT header. */
-        hurl.identity_map_range(acpi_xsdt_phys, Xsdt.sizeof, 0u);
+        Hurl.identity_map_range(acpi_xsdt_phys, Xsdt.sizeof, 0u);
         const(Xsdt) * xsdt = cast(const(Xsdt) *)acpi_xsdt_phys;
         if (xsdt.header.signature != XSDT_SIGNATURE)
         {
-            klog.writef("XSDT signature invalid\n");
+            Klog.writef("XSDT signature invalid\n");
             return;
         }
         /* Map the entire XSDT. */
-        hurl.identity_map_range(acpi_xsdt_phys, xsdt.header.length, 0u);
+        Hurl.identity_map_range(acpi_xsdt_phys, xsdt.header.length, 0u);
         size_t n_entries = (xsdt.header.length - xsdt.header.sizeof) / xsdt.tables[0].sizeof;
         for (size_t i = 0u; i < n_entries; i++)
         {
             ulong address = xsdt.tables[i];
-            hurl.identity_map_range(address, 4u, 0u);
+            Hurl.identity_map_range(address, 4u, 0u);
             uint signature = *cast(const(uint) *)address;
+            Klog.writefln("Found ACPI table %08x (%c%c%c%c)",
+                    signature,
+                    signature & 0xFFu,
+                    (signature >> 8u) & 0xFFu,
+                    (signature >> 16u) & 0xFFu,
+                    (signature >> 24u) & 0xFFu);
             if (signature == APIC_SIGNATURE)
             {
                 parse_apic_table(address);
@@ -83,9 +89,9 @@ struct acpi
     private static parse_apic_table(ulong address)
     {
         const(MadtHeader) * madt_header = cast(const(MadtHeader) *)address;
-        hurl.identity_map_range(address, madt_header.length, 0u);
+        Hurl.identity_map_range(address, madt_header.length, 0u);
         apic_address = madt_header.local_apic_address;
-        klog.writefln("Found 32-bit APIC address: 0x%x", apic_address);
+        Klog.writefln("Found 32-bit APIC address: 0x%x", apic_address);
         const(void) * madt_end = cast(const(void) *)(address + madt_header.length);
         const(MadtEntry) * madt_entry = cast(const(MadtEntry) *)(address + 0x2Cu);
         while (madt_entry < madt_end)
@@ -94,8 +100,8 @@ struct acpi
             if (madt_entry.type == 5u)
             {
                 /* Found a 64-bit Local APIC Address Override entry. */
+                Klog.writefln("Found 64-bit APIC address: 0x%x", apic_address);
                 memcpy(cast(void *)&apic_address, cast(const(void) *)madt_entry + 4u, 8u);
-                klog.writefln("Found 64-bit APIC address: 0x%x", apic_address);
             }
         }
     }

src/hulk/apic.d

@@ -7,11 +7,14 @@ import hulk.klog;
 import hulk.hurl;
 import hulk.acpi;
 import hulk.idt;
+import hulk.rtc;
 
-struct apic
+struct Apic
 {
     private enum uint PERIODIC_MODE = 0x2_0000u;
 
+    private enum ulong IRQ_RTC = 8u;
+
     static struct ApicRegister
     {
         public uint value;
@@ -52,31 +55,60 @@ struct apic
         ApicRegister divide_configuration;
     }
 
+    static struct IoApicRegisters
+    {
+        ApicRegister address;
+        ApicRegister data;
+    }
+
     private static __gshared ApicRegisters * apic_registers;
+    private static __gshared IoApicRegisters * io_apic_registers;
 
     public static void initialize()
     {
-        apic_registers = cast(ApicRegisters *)acpi.apic_address;
-        hurl.map(cast(ulong)apic_registers, cast(ulong)apic_registers,
+        apic_registers = cast(ApicRegisters *)Acpi.apic_address;
+        io_apic_registers = cast(IoApicRegisters *)0xFEC0_0000u;
+        Hurl.map(cast(ulong)apic_registers, cast(ulong)apic_registers,
                 PT_WRITABLE | PT_WRITE_THROUGH | PT_DISABLE_CACHE | PT_NO_EXECUTE);
-        klog.writefln("LAPIC ID: 0x%08x", apic_registers.lapic_id.value);
-        klog.writefln("LAPIC version: 0x%08x", apic_registers.lapic_version.value);
+        Hurl.map(cast(ulong)io_apic_registers, cast(ulong)io_apic_registers,
+                PT_WRITABLE | PT_WRITE_THROUGH | PT_DISABLE_CACHE | PT_NO_EXECUTE);
+        Klog.writefln("LAPIC ID: 0x%08x", apic_registers.lapic_id.value);
+        Klog.writefln("LAPIC version: 0x%08x", apic_registers.lapic_version.value);
         /* Enable local APIC to receive interrupts and set spurious interrupt
          * vector to 0xFF. */
-        apic_registers.spurious_interrupt_vector.value = 0x1FFu;
-        apic_registers.lvt_timer.value = idt.EXCEPTION_LAPIC_TIMER | PERIODIC_MODE;
-        apic_registers.lvt_lint[0].value = idt.EXCEPTION_LAPIC_LINT0;
-        apic_registers.lvt_lint[1].value = idt.EXCEPTION_LAPIC_LINT1;
-        apic_registers.divide_configuration.value = 3u;
+        apic_registers.spurious_interrupt_vector.value = 0x100u | Idt.INT_APIC_SPURIOUS;
+        apic_registers.lvt_timer.value = Idt.INT_APIC_TIMER;
+        apic_registers.lvt_lint[0].value = Idt.INT_APIC_LINT0;
+        apic_registers.lvt_lint[1].value = Idt.INT_APIC_LINT1;
+        /* Enable RTC interrupt. */
+        configure_io_apic_irq(IRQ_RTC, Idt.INT_APIC_BASE + IRQ_RTC);
     }
 
-    private static void eoi()
+    private static void configure_io_apic_irq(size_t io_apic_irq, size_t interrupt_id)
+    {
+        ulong entry = interrupt_id;
+        io_apic_registers.address.value = cast(uint)(0x10u + io_apic_irq * 2u);
+        io_apic_registers.data.value = entry & 0xFFFF_FFFFu;
+        io_apic_registers.address.value = cast(uint)(0x10u + io_apic_irq * 2u + 1u);
+        io_apic_registers.data.value = entry >> 32u;
+    }
+
+    public static void eoi()
     {
         apic_registers.eoi.value = 0u;
     }
 
     public static void isr(ulong vector)
     {
+        switch (vector)
+        {
+        case Idt.INT_APIC_BASE + IRQ_RTC:
+            Rtc.isr();
+            break;
+
+        default:
+            break;
+        }
         eoi();
     }
 }

src/hulk/console.d

@@ -6,7 +6,12 @@ module hulk.console;
 import hulk.fb;
 import hulk.kfont;
 
-struct console
+/**
+ * Represent the HULK console.
+ *
+ * Coordinate (0,0) is the top-left console position.
+ */
+struct Console
 {
     /** Console width in text columns. */
     private static __gshared size_t m_width;
@@ -25,8 +30,8 @@ struct console
      */
     public static void initialize()
     {
-        m_width = fb.width / kfont.advance;
-        m_height = fb.height / kfont.line_height;
+        m_width = Fb.width / Kfont.advance;
+        m_height = Fb.height / Kfont.line_height;
     }
 
     /**
@@ -34,7 +39,7 @@ struct console
      */
     public static void clear()
     {
-        fb.clear();
+        Fb.clear();
         m_x = 0u;
         m_y = 0u;
     }
@@ -64,10 +69,10 @@ struct console
         if (m_y == m_height)
         {
             m_y--;
-            fb.copy_rows_up(fb_y(m_height - 1u),
-                    (m_height - 1u) * kfont.line_height,
-                    kfont.line_height);
-            fb.rect(0u, fb_y(m_height - 1u), fb_x(m_width), kfont.line_height, 0u);
+            Fb.copy_rows_up(fb_y(1u),
+                    (m_height - 1u) * Kfont.line_height,
+                    Kfont.line_height);
+            Fb.rect(0u, fb_y(m_height - 1u), fb_x(m_width), Kfont.line_height, 0u);
         }
     }
 
@@ -80,8 +85,8 @@ struct console
      */
     private static void render_char(size_t x, size_t y, char ch)
     {
-        const(CharInfo) * ci = &kfont.chars[ch];
-        fb.blit_alpha_bitmap(fb_x(x) + ci.left, fb_y(y) + ci.top - ci.height, ci.bitmap, ci.width, ci.height);
+        const(CharInfo) * ci = &Kfont.chars[ch];
+        Fb.blit_alpha_bitmap(fb_x(x) + ci.left, fb_y(y) + ci.top, ci.bitmap, ci.width, ci.height);
     }
 
     /**
@@ -89,7 +94,7 @@ struct console
      */
     private static size_t fb_x(size_t x)
     {
-        return x * kfont.advance;
+        return x * Kfont.advance;
     }
 
     /**
@@ -97,6 +102,6 @@ struct console
      */
     private static size_t fb_y(size_t y)
     {
-        return fb.height - ((y + 1u) * kfont.line_height);
+        return y * Kfont.line_height;
     }
 }

src/hulk/cpu.d

@@ -221,9 +221,9 @@ ushort in16(ushort ioaddr)
     return __asm!ushort("inw %dx, %ax", "={ax},{dx}", ioaddr);
 }
 
-ulong in32(ushort ioaddr)
+uint in32(ushort ioaddr)
 {
-    return __asm!ulong("inl %dx, %eax", "={eax},{dx}", ioaddr);
+    return __asm!uint("inl %dx, %eax", "={eax},{dx}", ioaddr);
 }
 
 void out8(ushort ioaddr, ubyte v)
@@ -236,7 +236,7 @@ void out16(ushort ioaddr, ushort v)
     __asm("outw %ax, %dx", "{dx},{ax}", ioaddr, v);
 }
 
-void out32(ushort ioaddr, ulong v)
+void out32(ushort ioaddr, uint v)
 {
     __asm("outl %eax, %dx", "{dx},{eax}", ioaddr, v);
 }

src/hulk/fb.d

@@ -9,9 +9,11 @@ import hulk.kfont;
 /**
  * Represent a graphical frame buffer.
  *
+ * Coordinate (0,0) is the top-left corner of the framebuffer.
+ *
  * TODO: Handle other pixel formats. Currently only BGRx is supported.
  */
-struct fb
+struct Fb
 {
     /** Device frame buffer base address. */
     private __gshared static uint * m_device_buffer;
@@ -80,8 +82,8 @@ struct fb
     /**
      * Draw a solid rectangle on the framebuffer.
      *
-     * @param x X coordinate of left side of rectangle.
-     * @param y Y coordinate of bottom side of rectangle.
+     * @param x X coordinate of left of rectangle.
+     * @param y Y coordinate of top of rectangle.
      * @param width Width of rectangle.
      * @param height Height of rectangle.
      * @param color Color of rectangle.
@@ -100,7 +102,7 @@ struct fb
     /**
      * Draw a horizontal line.
      *
-     * @param x X coordinate of left side of line.
+     * @param x X coordinate of left of line.
      * @param y Y coordinate of line.
      * @param width Width of line.
      * @param color Color of line.
@@ -116,7 +118,7 @@ struct fb
      * Draw a vertical line.
      *
      * @param x X coordinate of line.
-     * @param y Y coordinate of bottom of line.
+     * @param y Y coordinate of top of line.
      * @param height Height of line.
      * @param color Color of line.
      */
@@ -127,81 +129,17 @@ struct fb
         {
             m_buffer1[buffer_index] = color;
             m_device_buffer[buffer_index] = color;
-            buffer_index -= m_stride;
+            buffer_index += m_stride;
         }
     }
 
-    /**
-     * Draw a character.
-     *
-     * @param x X coordinate of left side of character.
-     * @param y Y coordinate of bottom side of character.
-     * @param ch Character to draw.
-     * @param color Color of character.
-     */
-    static void character(int x, int y, char ch, uint color)
-    {
-        const(CharInfo) * ci = &kfont.chars[ch];
-        blend_alpha_bitmap(x + ci.left, y + kfont.baseline_offset + ci.top - ci.height, ci.bitmap, ci.width, ci.height, color);
-    }
-
-    /**
-     * Blend an 8-bit alpha bitmap to the framebuffer.
-     *
-     * @param x X coordinate of left side of target location.
-     * @param y Y coordinate of bottom side of target location.
-     * @param alpha_bitmap 8-bit alpha-channel bitmap.
-     * @param width Bitmap width.
-     * @param height Bitmap height.
-     * @param color Color to blend with alpha value.
-     */
-    static void blend_alpha_bitmap(size_t x, size_t y, const(ubyte) * alpha_bitmap,
-            size_t width, size_t height, uint color)
-    {
-        y += height - 1u;
-        size_t bitmap_index;
-        for (size_t iy = 0u; iy < height; iy++)
-        {
-            size_t row_buffer_index = buffer_index(x, y);
-            for (size_t ix = 0u; ix < width; ix++)
-            {
-                size_t buffer_index = row_buffer_index + ix;
-                ubyte alpha = alpha_bitmap[bitmap_index];
-                uint current_color = m_buffer1[buffer_index];
-                uint in_color_scaled = scale_color(color, alpha);
-                uint old_color_scaled = scale_color(current_color, 255u - alpha);
-                uint new_color = old_color_scaled + in_color_scaled;
-                m_buffer1[buffer_index] = new_color;
-                bitmap_index++;
-            }
-            memcpy32(&m_device_buffer[row_buffer_index], &m_buffer1[row_buffer_index], width);
-            y--;
-        }
-    }
-
-    /**
-     * Blend an 8-bit alpha bitmap to the framebuffer.
-     *
-     * @param x X coordinate of left side of target location.
-     * @param y Y coordinate of bottom side of target location.
-     * @param alpha_bitmap 8-bit alpha-channel bitmap.
-     * @param width Bitmap width.
-     * @param height Bitmap height.
-     * @param color Color to blend with alpha value.
-     */
-    static void blend_alpha_bitmap(size_t x, size_t y, const(ubyte)[] alpha_bitmap,
-            size_t width, size_t height, uint color)
-    {
-        blend_alpha_bitmap(x, y, alpha_bitmap.ptr, width, height, color);
-    }
-
     /**
      * Blit an 8-bit alpha bitmap to the framebuffer.
      * The foreground will be white (based on the alpha value), and the
      * background black.
      *
-     * @param x X coordinate of left side of target location.
-     * @param y Y coordinate of bottom side of target location.
+     * @param x X coordinate of left of target location.
+     * @param y Y coordinate of top of target location.
      * @param alpha_bitmap 8-bit alpha-channel bitmap.
      * @param width Bitmap width.
      * @param height Bitmap height.
@@ -209,7 +147,6 @@ struct fb
     static void blit_alpha_bitmap(size_t x, size_t y, const(ubyte) * alpha_bitmap,
             size_t width, size_t height)
     {
-        y += height - 1u;
         size_t bitmap_index;
         for (size_t iy = 0u; iy < height; iy++)
         {
@@ -222,7 +159,7 @@ struct fb
                 bitmap_index++;
             }
             memcpy32(&m_device_buffer[row_buffer_index], &m_buffer1[row_buffer_index], width);
-            y--;
+            y++;
         }
     }
 
@@ -231,8 +168,8 @@ struct fb
      * The foreground will be white (based on the alpha value), and the
      * background black.
      *
-     * @param x X coordinate of left side of target location.
-     * @param y Y coordinate of bottom side of target location.
+     * @param x X coordinate of left of target location.
+     * @param y Y coordinate of top of target location.
      * @param alpha_bitmap 8-bit alpha-channel bitmap.
      * @param width Bitmap width.
      * @param height Bitmap height.
@@ -246,14 +183,14 @@ struct fb
     /**
      * Copy framebuffer rows up in the framebuffer.
      *
-     * @param y Y coordinate of bottom side of region to copy up.
+     * @param y Y coordinate of top of region to copy up.
      * @param height Height of region to copy up.
      * @param offset Number of rows to copy region up by.
      */
     static void copy_rows_up(size_t y, size_t height, size_t offset)
     {
-        size_t dest_buffer_index = buffer_index(0u, y + height + offset - 1u);
-        size_t src_buffer_index = buffer_index(0u, y + height - 1u);
+        size_t dest_buffer_index = buffer_index(0u, y - offset);
+        size_t src_buffer_index = buffer_index(0u, y);
         memcpy32(&m_buffer1[dest_buffer_index],
                  &m_buffer1[src_buffer_index],
                  (m_stride * height));
@@ -262,21 +199,6 @@ struct fb
                 (m_stride * height));
     }
 
-    /**
-     * Scale a color value by an alpha amount.
-     *
-     * @param color Color value.
-     * @param alpha Alpha amount.
-     *
-     * @return Scaled color value.
-     */
-    private static uint scale_color(uint color, ubyte alpha)
-    {
-        return ((((color & 0xFFu) * alpha) >> 8u) & 0xFFu) |
-               ((((color & 0xFF00u) * alpha) >> 8u) & 0xFF00u) |
-               ((((color & 0xFF0000u) * alpha) >> 8u) & 0xFF0000u);
-    }
-
     /**
      * Return the buffer index for the given X and Y coordinates.
      *
@@ -287,6 +209,6 @@ struct fb
      */
     private static size_t buffer_index(size_t x, size_t y)
     {
-        return (m_height - y - 1u) * m_stride + x;
+        return y * m_stride + x;
     }
 }

src/hulk/gdt.d

@@ -5,7 +5,7 @@ module hulk.gdt;
 
 import ldc.llvmasm;
 
-struct gdt
+struct Gdt
 {
     struct gdtr_t
     {

src/hulk/hippo.d

@@ -7,7 +7,7 @@
  */
 module hulk.hippo;
 
-struct hippo
+struct Hippo
 {
     /**
      * Linked list node entry for a physical page.

src/hulk/hulk.d

@@ -20,6 +20,8 @@ import ldc.llvmasm;
 import hulk.pic;
 import hulk.acpi;
 import hulk.apic;
+import hulk.rtc;
+import hulk.serial;
 
 extern extern(C) __gshared ubyte _hulk_bss_size;
 
@@ -28,9 +30,9 @@ private __gshared HulkHeader hulk_header = {
     &_hulk_bss_size, /* hulk_bss_size */
     &hulk_start, /* entry */
     16u * 1024u, /* stack_size */
-    HULK_VIRTUAL_BASE_ADDRESS, /* virt_base */
-    HULK_VIRTUAL_STACK_TOP_ADDRESS, /* virt_stack_top */
-    HULK_VIRTUAL_FRAMEBUFFER_ADDRESS, /* virt_fb_buffer */
+    Hurl.HULK_BASE, /* virt_base */
+    Hurl.HULK_STACK_TOP, /* virt_stack_top */
+    Hurl.HULK_FRAMEBUFFER, /* virt_fb_buffer */
 };
 
 private void initialize_cpu()
@@ -55,24 +57,26 @@ void hulk_start()
 {
     cli();
     initialize_cpu();
-    gdt.initialize();
-    idt.initialize();
-    fb.initialize(cast(uint *)HULK_VIRTUAL_FRAMEBUFFER_ADDRESS,
+    Serial.initialize();
+    Gdt.initialize();
+    Idt.initialize();
+    Fb.initialize(cast(uint *)Hurl.HULK_FRAMEBUFFER,
             cast(uint *)hulk_header.bootinfo.fb_buffer1_phys,
             hulk_header.bootinfo.fb.width,
             hulk_header.bootinfo.fb.height,
             hulk_header.bootinfo.fb.stride);
-    console.initialize();
-    console.clear();
-    klog.initialize();
+    Console.initialize();
+    Console.clear();
+    Klog.initialize();
 
-    klog.writefln("Welcome to HULK, the HOS UltraLight Kernel!");
+    Klog.writefln("Welcome to HULK, the HOS UltraLight Kernel!");
 
-    hurl.initialize(&hulk_header);
-    pci.initialize();
-    pic.initialize();
-    acpi.initialize(hulk_header.bootinfo.acpi_xsdt_phys);
-    apic.initialize();
+    Hurl.initialize(&hulk_header);
+    Pci.initialize();
+    Pic.initialize();
+    Acpi.initialize(hulk_header.bootinfo.acpi_xsdt_phys);
+    Apic.initialize();
+    Rtc.initialize();
     sti();
 
     for (;;)

src/hulk/hulk.ld

@@ -16,6 +16,7 @@ SECTIONS
     .text :
     {
         *(.text)
+        *(.text.*)
     }
 
     . = ALIGN(4K);
@@ -25,6 +26,7 @@ SECTIONS
     .rodata :
     {
         *(.rodata)
+        *(.rodata.*)
     }
 
     . = ALIGN(4K);
@@ -35,6 +37,7 @@ SECTIONS
     .data :
     {
         *(.data)
+        *(.data.*)
     }
 
     . = ALIGN(4K);
@@ -46,6 +49,7 @@ SECTIONS
     {
         *(COMMON)
         *(.bss)
+        *(.bss.*)
     }
 
     . = ALIGN(4K);

src/hulk/hurl/a1.d

@@ -0,0 +1,64 @@
+/**
+ * A1 memory allocator.
+ */
+module hulk.hurl.a1;
+
+import hulk.hurl;
+import hulk.hippo;
+import hulk.util;
+import hulk.pagetable;
+
+/**
+ * The A1 memory allocator is a one-shot memory allocator for kernel memory
+ * that is allocated but never freed.
+ */
+struct A1
+{
+    /**
+     * Number of bytes allocated in the A1 region so far.
+     */
+    private static __gshared size_t allocated;
+
+    /**
+     * Allocate memory.
+     *
+     * @param size
+     *   Size of memory to allocate.
+     *
+     * @return Address of allocated memory. This address will always be aligned
+     *   to a multiple of 16 bytes.
+     */
+    public static void * allocate(size_t size)
+    {
+        /* Round size up to a multiple of 16. */
+        size = round_up_power_2(size, 16u);
+
+        ulong address = Hurl.A1_BASE + allocated;
+
+        ulong current_limit = round_up_power_2(address, PAGE_SIZE);
+
+        allocated += size;
+
+        ulong desired_limit = round_up_power_2(Hurl.A1_BASE + allocated, PAGE_SIZE);
+
+        while (desired_limit > current_limit)
+        {
+            void * page = Hippo.allocate_page();
+            Hurl.map(current_limit, page, PT_WRITABLE);
+            current_limit += PAGE_SIZE;
+        }
+
+        return cast(void *)address;
+    }
+
+    /**
+     * Allocate memory to store an instance of a given type.
+     *
+     * @return Address of allocated memory. This address will always be aligned
+     *   to a multiple of 16 bytes.
+     */
+    public static T * allocate(T)()
+    {
+        return cast(T *)allocate(T.sizeof);
+    }
+}

src/hulk/hurl/hurl.d

@@ -3,7 +3,7 @@
  *
  * HURL provides virtual memory management for HULK.
  */
-module hulk.hurl;
+module hulk.hurl.hurl;
 
 public import hulk.pagetable;
 import hulk.cpu;
@@ -13,18 +13,22 @@ import hulk.klog;
 import hulk.bootinfo;
 import hulk.header;
 import hulk.linker_addresses;
+import hulk.util;
 
-/** HULK virtual base address. */
-enum ulong HULK_VIRTUAL_BASE_ADDRESS = 0xFFFF_8000_0000_0000u;
-
-/** HULK virtual stack top address. */
-enum ulong HULK_VIRTUAL_STACK_TOP_ADDRESS = 0xFFFF_A000_0000_0000u;
-
-/** HULK virtual framebuffer address. */
-enum ulong HULK_VIRTUAL_FRAMEBUFFER_ADDRESS = 0xFFFF_A000_0000_0000u;
-
-struct hurl
+struct Hurl
 {
+    /** HULK base address. */
+    enum ulong HULK_BASE = 0xFFFF_8000_0000_0000u;
+
+    /** HULK stack top address. */
+    enum ulong HULK_STACK_TOP = 0xFFFF_8001_0000_0000u;
+
+    /** HULK framebuffer address. */
+    enum ulong HULK_FRAMEBUFFER = 0xFFFF_8001_0000_0000u;
+
+    /** A1 allocator range base address. */
+    enum ulong A1_BASE = 0xFFFF_8002_0000_0000u;
+
     /**
      * Pointer to the base page table.
      */
@@ -45,7 +49,7 @@ struct hurl
                 physical_address_limit,
                 PT_WRITABLE | PT_NO_EXECUTE);
         ulong phys_address = header.bootinfo.hulk_phys;
-        ulong virt_address = HULK_VIRTUAL_BASE_ADDRESS;
+        ulong virt_address = HULK_BASE;
         /* Map HULK header region. */
         map_range(virt_address,
                 phys_address,
@@ -79,12 +83,12 @@ struct hurl
                 LinkerAddresses.hulk_bss_size,
                 PT_WRITABLE | PT_NO_EXECUTE);
         /* Map HULK stack. */
-        map_range(HULK_VIRTUAL_STACK_TOP_ADDRESS - header.stack_size,
+        map_range(HULK_STACK_TOP - header.stack_size,
                 header.bootinfo.stack_phys,
                 header.stack_size,
                 PT_WRITABLE | PT_NO_EXECUTE);
         /* Map device framebuffer. */
-        map_range(HULK_VIRTUAL_FRAMEBUFFER_ADDRESS,
+        map_range(HULK_FRAMEBUFFER,
                 cast(ulong)header.bootinfo.fb.buffer,
                 header.bootinfo.fb.height * header.bootinfo.fb.stride * 4u,
                 PT_WRITABLE | PT_NO_EXECUTE);
@@ -121,7 +125,7 @@ struct hurl
                 reclaimed_pages += reclaim_bootloader_page_table_pages(pte.follow(), level + 1u);
             }
         }
-        hippo.free_page(pt);
+        Hippo.free_page(pt);
         reclaimed_pages++;
         return reclaimed_pages;
     }
@@ -152,7 +156,7 @@ struct hurl
          */
         size_t usable_memory;
         size_t physical_address_limit;
-        const(size_t) fb_size = (header.bootinfo.fb.height * header.bootinfo.fb.stride * 4u + PAGE_SIZE - 1u) & ~(PAGE_SIZE - 1u);
+        const(size_t) fb_size = round_up_power_2(header.bootinfo.fb.height * header.bootinfo.fb.stride * 4u, PAGE_SIZE);
         ulong[2][2] reserved = [
             [header.bootinfo.hulk_phys, LinkerAddresses.hulk_binary_size],
             [cast(ulong)header.bootinfo.fb.buffer, fb_size],
@@ -186,7 +190,7 @@ struct hurl
                     }
                     if (!is_reserved)
                     {
-                        hippo.free_page(phys);
+                        Hippo.free_page(phys);
                     }
                     phys += PAGE_SIZE;
                 }
@@ -213,11 +217,11 @@ struct hurl
         usable_memory += LinkerAddresses.hulk_bss_size;
         usable_memory += header.stack_size;
         usable_memory += fb_size;
-        klog.writefln("Usable memory: %uKB", usable_memory >> 10u);
-        klog.writefln("Kernel size: %uKB", (LinkerAddresses.hulk_binary_size + LinkerAddresses.hulk_bss_size + header.stack_size) >> 10u);
+        Klog.writefln("Usable memory: %uKB", usable_memory >> 10u);
+        Klog.writefln("Kernel size: %uKB", (LinkerAddresses.hulk_binary_size + LinkerAddresses.hulk_bss_size + header.stack_size) >> 10u);
     }
 
-    public static void map(T, U)(T virtual, U physical, ulong flags)
+    public static void map(ulong virtual, ulong physical, ulong flags)
     {
         PageTable * pt = m_pt_base;
         for (size_t level = 0; level < 4u; level++)
@@ -244,7 +248,12 @@ struct hurl
         }
     }
 
-    public static void map_range(size_t virtual, size_t physical, size_t length, ulong flags)
+    public static void map(T, U)(T virtual, U physical, ulong flags)
+    {
+        map(cast(ulong)virtual, cast(ulong)physical, flags);
+    }
+
+    public static void map_range(ulong virtual, ulong physical, size_t length, ulong flags)
     {
         size_t end = virtual + length;
         while (virtual < end)
@@ -255,23 +264,33 @@ struct hurl
         }
     }
 
-    public static void identity_map_range(size_t address, size_t length, ulong flags)
+    public static void map_range(T, U)(T virtual, U physical, size_t length, ulong flags)
+    {
+        map_range(cast(ulong)virtual, cast(ulong)physical, length, flags);
+    }
+
+    public static void identity_map_range(ulong address, size_t length, ulong flags)
     {
         size_t end = address + length;
-        for (size_t page = address & ~0xFFFu; page < end; page += PAGE_SIZE)
+        for (size_t page = address & 0xFFFF_FFFF_FFFF_F000u; page < end; page += PAGE_SIZE)
         {
             map(page, page, flags);
         }
     }
 
+    public static void identity_map_range(T)(T address, size_t length, ulong flags)
+    {
+        identity_map_range(cast(ulong)address, length, flags);
+    }
+
     public static void debug_lookup(void * address)
     {
-        klog.writefln("Debugging page table lookup of 0x%x", address);
+        Klog.writefln("Debugging page table lookup of 0x%x", address);
         PageTable * pt = m_pt_base;
         for (size_t level = 0; level < 4u; level++)
         {
             PageTableEntry pte = *pt.entry(address, level);
-            klog.writefln("Level %u, index %u, entry = 0x%x", level, pt.index(address, level), pte);
+            Klog.writefln("Level %u, index %u, entry = 0x%x", level, pt.index(address, level), pte);
             if (pte.present)
             {
                 pt = pte.follow();
@@ -289,7 +308,7 @@ struct hurl
 
     private static PageTable * allocate_pt()
     {
-        PageTable * pt = cast(PageTable *)hippo.allocate_page();
+        PageTable * pt = cast(PageTable *)Hippo.allocate_page();
         memset64(pt, 0u, PAGE_SIZE / 8u);
         return pt;
     }

src/hulk/hurl/package.d

@@ -0,0 +1,3 @@
+module hulk.hurl;
+
+public import hulk.hurl.hurl;

src/hulk/idt.d

@@ -10,11 +10,16 @@ import hulk.console;
 import hulk.klog;
 import hulk.apic;
 
-struct idt
+struct Idt
 {
-    public static enum ulong EXCEPTION_LAPIC_TIMER = 0x70u;
-    public static enum ulong EXCEPTION_LAPIC_LINT0 = 0x71u;
-    public static enum ulong EXCEPTION_LAPIC_LINT1 = 0x72u;
+    /* The I/O APIC is configured to map IRQ 0 to interrupt 64 (0x40). */
+    public static enum ulong INT_APIC_BASE = 0x40u; /* IRQ 0 */
+    public static enum ulong INT_APIC_COUNT = 24u;
+
+    public static enum ulong INT_APIC_TIMER = 0x70u;
+    public static enum ulong INT_APIC_LINT0 = 0x71u;
+    public static enum ulong INT_APIC_LINT1 = 0x72u;
+    public static enum ulong INT_APIC_SPURIOUS = 0xFFu;
 
     struct idtr_t
     {
@@ -91,7 +96,7 @@ struct idt
             ((offset & 0xFFFF_0000u) << 32u) |
             (dpl << 45u) |
             ((trap ? 1uL : 0uL) << 40u) |
-            (gdt.SELECTOR_KERNEL_CODE << 16u) |
+            (Gdt.SELECTOR_KERNEL_CODE << 16u) |
             (offset & 0xFFFFu);
         idt[index][1] = offset >> 32u;
     }
@@ -99,15 +104,25 @@ struct idt
 
 public extern(C) void isr(ulong vector, ulong arg)
 {
-    if ((idt.EXCEPTION_LAPIC_TIMER <= vector) && (vector <= idt.EXCEPTION_LAPIC_LINT1))
+    if ((vector >= Idt.INT_APIC_BASE) && (vector < (Idt.INT_APIC_BASE + Idt.INT_APIC_COUNT)))
     {
-        apic.isr(vector);
+        Apic.isr(vector);
     }
     else
     {
-        console.clear();
-        fb.clear(0xFF8000u);
-        klog.writefln("ISR %u, 0x%x", vector, arg);
+        switch (vector)
+        {
+        case Idt.INT_APIC_TIMER:
+        case Idt.INT_APIC_LINT0:
+        case Idt.INT_APIC_LINT1:
+        case Idt.INT_APIC_SPURIOUS:
+            Apic.isr(vector);
+            break;
+
+        default:
+            Console.clear();
+            Fb.clear(0xFF8000u);
+            Klog.writefln("ISR %u, 0x%x", vector, arg);
             __asm("cli", "");
             for (;;)
             {
@@ -115,3 +130,4 @@ public extern(C) void isr(ulong vector, ulong arg)
             }
         }
     }
+}

src/hulk/klog.d

@@ -7,7 +7,7 @@ import core.stdc.stdarg;
 import hulk.console;
 static import hulk.writef;
 
-struct klog
+struct Klog
 {
     /**
      * Kernel buffer size log.
@@ -40,7 +40,7 @@ struct klog
     public static void writef(string s, va_list args)
     {
         hulk.writef.writef(s, args, function void(ubyte ch) {
-                    console.write(ch);
+                    Console.write(ch);
                 });
     }
 
@@ -58,7 +58,7 @@ struct klog
     }
 
     /**
-     * Write a formatted string and newline to the console.
+     * Write a formatted string and newline to the kernel log.
      *
      * @param s Format string.
      */

src/hulk/mtrr.d

@@ -31,7 +31,7 @@ enum ulong MTRRPHYSBASE_TYPE_MASK = 0xFFu;
 enum ulong MTRRPHYSMASK_PHYSMASK_MASK = 0x000F_FFFF_FFFF_F000u;
 enum ulong MTRRPHYSMASK_VALID = 0x800u;
 
-struct mtrr
+struct Mtrr
 {
     public static void initialize()
     {
@@ -41,7 +41,7 @@ struct mtrr
         cpuid1(&ebx, &ecx, &edx);
         if ((edx & CPUID_1_EDX_MTRR) == 0u)
         {
-            klog.writefln("CPU does not support MTRR");
+            Klog.writefln("CPU does not support MTRR");
             return;
         }
         const(ulong) mtrrcap = rdmsr(MSR_MTRRCAP);

src/hulk/pagetable.d

@@ -183,3 +183,11 @@ struct PageTable
     }
 }
 static assert(PageTable.sizeof == 4096u);
+
+/**
+ * Get the base address of the page containing the given address.
+ */
+T page_address(T)(T address)
+{
+    return cast(T)(cast(ulong)address & ~(PAGE_SIZE - 1u));
+}

src/hulk/pci.d

@@ -2,8 +2,12 @@ module hulk.pci;
 
 import hulk.cpu;
 import hulk.klog;
+import hulk.hurl;
+import hulk.hurl.a1;
+import hulk.range;
+import hulk.usb.xhci;
 
-struct pci
+struct Pci
 {
     /* IO address for PCI configuration address. */
     enum IO_ADDR_CONFIG_ADDRESS = 0xCF8u;
@@ -11,38 +15,216 @@ struct pci
     /* IO address for PCI configuration data. */
     enum IO_ADDR_CONFIG_DATA = 0xCFCu;
 
-    private static ulong read_config_register(ulong bus_id, ulong device_id, ulong register_id)
+    struct Address
     {
-        ulong addr = 0x8000_0000u | (bus_id << 16u) | (device_id << 11u) | (register_id << 2u);
-        out32(IO_ADDR_CONFIG_ADDRESS, addr);
+        /** Bus number (0-255). */
+        ubyte bus_nr;
+
+        /** Device number (0-31). */
+        ubyte device_nr;
+
+        /** Function number (0-7). */
+        ubyte function_nr;
+    }
+
+    struct Device
+    {
+        Address address;
+        ushort vendor_id;
+        ushort device_id;
+        ubyte class_id;
+        ubyte subclass_id;
+        ubyte if_id;
+        bool multifunction;
+        ubyte header_type;
+        Range[6] memory_ranges;
+
+        void initialize(Address address, ushort vendor_id, ushort device_id)
+        {
+            this.address = address;
+            this.vendor_id = vendor_id;
+            this.device_id = device_id;
+            uint reg2 = read_config_register(address, 2u);
+            class_id = (reg2 >> 24u) & 0xFFu;
+            subclass_id = (reg2 >> 16u) & 0xFFu;
+            if_id = (reg2 >> 8u) & 0xFFu;
+            Klog.writefln("Found PCI device %04x:%04x (%02x:%02x:%02x) at %02u:%02u.%u",
+                    vendor_id, device_id,
+                    class_id, subclass_id, if_id,
+                    address.bus_nr, address.device_nr, address.function_nr);
+            uint reg3 = read_config_register(address, 3u);
+            header_type = (reg3 >> 16u) & 0x7Fu;
+            multifunction = (address.function_nr == 0u) && ((reg3 & (1u << 23u)) != 0u);
+
+            if (header_type == 0u)
+            {
+                map_memory_regions();
+            }
+
+            spawn_device_instance();
+        }
+
+        private void map_memory_regions()
+        {
+            size_t range_index;
+            uint[2] r;
+            uint[2] s;
+            for (uint reg_no = 4u; reg_no <= 9u; reg_no++)
+            {
+                /* Read the BAR. */
+                r[0] = read_config_register(address, reg_no);
+                /* Skip zeroed BARs. */
+                if (r[0] == 0u)
+                {
+                    continue;
+                }
+                /* Skip I/O BARs. */
+                if ((r[0] & 1u) != 0u)
+                {
+                    continue;
+                }
+                bool is_64bit;
+                uint bar_type = (r[0] >> 1u) & 0x3u;
+                if (bar_type == 0u)
+                {
+                    /* 32-bit region. */
+                    r[1] = 0u;
+                }
+                else if ((bar_type == 2u) && (reg_no < 9u))
+                {
+                    /* 64-bit region. */
+                    is_64bit = true;
+                    r[1] = read_config_register(address, reg_no + 1);
+                }
+                else
+                {
+                    continue;
+                }
+
+                /* Determine the region length. */
+                write_config_register(address, reg_no, 0xFFFF_FFFFu);
+                s[0] = read_config_register(address, reg_no);
+                write_config_register(address, reg_no, r[0]);
+                if (is_64bit)
+                {
+                    write_config_register(address, reg_no + 1, 0xFFFF_FFFFu);
+                    s[1] = read_config_register(address, reg_no + 1);
+                    write_config_register(address, reg_no + 1, r[1]);
+                }
+                else
+                {
+                    s[1] = 0xFFFF_FFFFu;
+                }
+                ulong mm_region_address = (cast(ulong)r[0] & 0xFFFF_FFF0u) | (cast(ulong)r[1] << 32u);
+                ulong length = ~((cast(ulong)s[0] & 0xFFFF_FFF0u) | (cast(ulong)s[1] << 32u)) + 1u;
+                ulong flags = (r[0] & 0x8) != 0u ? PT_WRITE_THROUGH : 0u;
+                Hurl.identity_map_range(mm_region_address, length, flags);
+                memory_ranges[range_index].address = mm_region_address;
+                memory_ranges[range_index].length = length;
+                range_index++;
+                if (is_64bit)
+                {
+                    reg_no++;
+                }
+            }
+        }
+
+        private void spawn_device_instance()
+        {
+            switch (class_id)
+            {
+            case SerialBusController.ID:
+                switch (subclass_id)
+                {
+                case SerialBusController.USBController.ID:
+                    switch (if_id)
+                    {
+                    case SerialBusController.USBController.XHCIController.ID:
+                        XHCI.build(&this);
+                        break;
+
+                    default:
+                        break;
+                    }
+                    break;
+
+                default:
+                    break;
+                }
+                break;
+
+            default:
+                break;
+            }
+        }
+    }
+
+    struct SerialBusController
+    {
+        enum ID = 0x0Cu;
+
+        struct USBController
+        {
+            enum ID = 0x03u;
+
+            struct XHCIController
+            {
+                enum ID = 0x30u;
+            }
+        }
+    }
+
+    private static uint read_config_register(Address address, uint register_id)
+    {
+        uint cfg_addr = 0x8000_0000u |
+            (address.bus_nr << 16u) |
+            (address.device_nr << 11u) |
+            (address.function_nr << 8u) |
+            (register_id << 2u);
+        out32(IO_ADDR_CONFIG_ADDRESS, cfg_addr);
         return in32(IO_ADDR_CONFIG_DATA);
     }
 
-    private static void scan(ulong bus_id, ulong device_id)
+    private static void write_config_register(Address address, uint register_id, uint value)
     {
-        ulong reg0 = read_config_register(bus_id, device_id, 0u);
+        uint cfg_addr = 0x8000_0000u |
+            (address.bus_nr << 16u) |
+            (address.device_nr << 11u) |
+            (address.function_nr << 8u) |
+            (register_id << 2u);
+        out32(IO_ADDR_CONFIG_ADDRESS, cfg_addr);
+        out32(IO_ADDR_CONFIG_DATA, value);
+    }
+
+    private static void scan(Address address)
+    {
+        ulong reg0 = read_config_register(address, 0u);
         if (reg0 != 0xFFFFFFFFu)
         {
-            ulong reg2 = read_config_register(bus_id, device_id, 2u);
-            klog.writefln("Found PCI device %04x:%04x (%02x:%02x:%02x) at %02u:%02u",
-                    (reg0 & 0xFFFFu), (reg0 >> 16u),
-                    (reg2 >> 24u) & 0xFFu,
-                    (reg2 >> 16u) & 0xFFu,
-                    (reg2 >> 8u) & 0xFFu,
-                    bus_id, device_id);
+            ushort vendor_id = reg0 & 0xFFFFu;
+            ushort device_id = (reg0 >> 16u) & 0xFFFFu;
+            Device * device = A1.allocate!Device();
+            device.initialize(address, vendor_id, device_id);
+            if (device.multifunction)
+            {
+                for (address.function_nr = 1u; address.function_nr < 8u; address.function_nr++)
+                {
+                    scan(address);
+                }
+            }
         }
     }
 
     public static void initialize()
     {
-        klog.writefln("Scanning PCI devices...");
-        for (ulong bus_id = 0u; bus_id < 256u; bus_id++)
+        Klog.writefln("Scanning PCI devices...");
+        for (uint bus_nr = 0u; bus_nr < 256u; bus_nr++)
         {
-            for (ulong device_id = 0u; device_id < 32u; device_id++)
+            for (ubyte device_nr = 0u; device_nr < 32u; device_nr++)
             {
-                scan(bus_id, device_id);
+                scan(Address(cast(ubyte)bus_nr, device_nr, 0u));
             }
         }
-        klog.writefln("PCI scan complete.");
+        Klog.writefln("PCI scan complete.");
     }
 }

src/hulk/pic.d

@@ -5,7 +5,7 @@ module hulk.pic;
 
 import hulk.cpu;
 
-struct pic
+struct Pic
 {
     public static void initialize()
     {

src/hulk/pit.d

@@ -0,0 +1,42 @@
+/**
+ * PIT (Programmable Interval Timer) functionality.
+ */
+module hulk.pit;
+
+import hulk.cpu;
+import hulk.klog;
+
+struct Pit
+{
+    /** PIT input frequency in 1/1000 Hz. */
+    private enum ulong PIT_FREQUENCY_1000HZ = 1_193_181_667u;
+    private enum ulong TARGET_INTERRUPT_HZ = 100u;
+    private enum ulong TARGET_INTERRUPT_1000HZ = TARGET_INTERRUPT_HZ * 1000u;
+    private enum ulong PIT_DIVIDER = (PIT_FREQUENCY_1000HZ + TARGET_INTERRUPT_1000HZ / 2u) / TARGET_INTERRUPT_1000HZ;
+
+    /** PIT channel 0 I/O port. */
+    private enum ubyte PORT_CH_0 = 0x40u;
+    /** PIT channel 1 I/O port. */
+    private enum ubyte PORT_CH_1 = 0x41u;
+    /** PIT channel 2 I/O port. */
+    private enum ubyte PORT_CH_2 = 0x42u;
+    /** PIT mode/command register I/O port. */
+    private enum ubyte PORT_MC = 0x43u;
+
+    private enum ubyte MC_CH_0 = 0x00u;
+    private enum ubyte MC_LO_HI = 0x30u;
+    private enum ubyte MC_RATE_GENERATOR = 0x04u;
+    private enum ubyte MC_BINARY = 0x00u;
+
+    public static void initialize()
+    {
+        out8(PORT_MC, MC_CH_0 | MC_LO_HI | MC_RATE_GENERATOR | MC_BINARY);
+        out8(PORT_CH_0, PIT_DIVIDER & 0xFFu);
+        out8(PORT_CH_0, PIT_DIVIDER >> 8u);
+    }
+
+    public static void isr()
+    {
+        Klog.writefln("PIT ISR");
+    }
+}

src/hulk/range.d

@@ -0,0 +1,27 @@
+module hulk.range;
+
+/**
+ * Representation of a memory range.
+ */
+struct Range
+{
+    /** Range base address. */
+    void * _address;
+
+    /** Range length. */
+    size_t length;
+
+    /** Set the range address. */
+    @property void * address(T)(T a)
+    {
+        static assert(T.sizeof == size_t.sizeof);
+        _address = cast(void *)a;
+        return _address;
+    }
+
+    /** Get the range address. */
+    @property void * address()
+    {
+        return _address;
+    }
+}

src/hulk/rtc.d

@@ -0,0 +1,149 @@
+/**
+ * RTC (Real-Time Clock) functionality.
+ */
+module hulk.rtc;
+
+import hulk.cpu;
+import hulk.klog;
+
+struct Rtc
+{
+    private enum ubyte PORT_SELECT = 0x70u;
+    private enum ubyte PORT_DATA = 0x71u;
+
+    private enum ubyte DISABLE_NMI = 0x80u;
+
+    private enum ubyte REG_RTC_SECONDS = 0x0u;
+    private enum ubyte REG_RTC_MINUTES = 0x2u;
+    private enum ubyte REG_RTC_HOURS = 0x4u;
+    private enum ubyte REG_RTC_DAY = 0x7u;
+    private enum ubyte REG_RTC_MONTH = 0x8u;
+    private enum ubyte REG_RTC_YEAR = 0x9u;
+    private enum ubyte REG_SR_A = 0xAu;
+    private enum ubyte REG_SR_B = 0xBu;
+    private enum ubyte REG_SR_C = 0xCu;
+
+    private enum ubyte SR_A_RTC_UPDATE_IN_PROGRESS = 0x80u;
+    private enum ubyte SR_B_24HOUR = 0x02u;
+    private enum ubyte SR_B_BINARY = 0x04u;
+    private enum ubyte SR_B_ENABLE_IRQ = 0x40u;
+
+    private static __gshared bool rtc_24hour_mode;
+    private static __gshared bool rtc_binary_mode;
+
+    static struct time
+    {
+        public ubyte year;
+        public ubyte month;
+        public ubyte day;
+        public ubyte hour;
+        public ubyte minute;
+        public ubyte second;
+    }
+
+    public static void initialize()
+    {
+        /* Enable IRQ 8 to receive RTC interrupts. */
+        ubyte sr_b = read_register(REG_SR_B, true);
+        write_register(REG_SR_B, sr_b | SR_B_ENABLE_IRQ, true);
+
+        /* Record RTC mode flags from status register B. */
+        rtc_24hour_mode = (sr_b & SR_B_24HOUR) != 0u;
+        rtc_binary_mode = (sr_b & SR_B_BINARY) != 0u;
+
+        /* Read the current system time. */
+        time t = read_rtc_time();
+        Klog.writefln("System time is 20%02u-%02u-%02u %02u:%02u:%02u",
+                t.year, t.month, t.day, t.hour, t.minute, t.second);
+
+        /* Send EOI to enable more RTC interrupts and re-enable NMIs. */
+        eoi();
+    }
+
+    private static ubyte read_register(ubyte register, bool disable_nmi = false)
+    {
+        out8(PORT_SELECT, register | (disable_nmi ? DISABLE_NMI : 0u));
+        return in8(PORT_DATA);
+    }
+
+    private static void write_register(ubyte register, ubyte value, bool disable_nmi = false)
+    {
+        out8(PORT_SELECT, register | (disable_nmi ? DISABLE_NMI : 0u));
+        out8(PORT_DATA, value);
+    }
+
+    private static void eoi()
+    {
+        /* Read from status register C to clear the interrupt. */
+        read_register(REG_SR_C);
+    }
+
+    public static void isr()
+    {
+        static __gshared ulong count;
+        static __gshared ulong seconds;
+        count++;
+        if ((count % 1024) == 0u)
+        {
+            seconds++;
+        }
+        eoi();
+    }
+
+    private static time read_rtc_time()
+    {
+        time[2] times;
+        size_t reads;
+        do
+        {
+            times[reads & 1] = read_rtc_time_unsafe();
+            reads++;
+        } while ((reads < 2u) || (times[0] != times[1]));
+        return times[0];
+    }
+
+    private static time read_rtc_time_unsafe()
+    {
+        time t;
+        while ((read_register(REG_SR_A) & SR_A_RTC_UPDATE_IN_PROGRESS) != 0u)
+        {
+        }
+        t.year = read_rtc_time_register(REG_RTC_YEAR);
+        t.month = read_rtc_time_register(REG_RTC_MONTH);
+        t.day = read_rtc_time_register(REG_RTC_DAY);
+        t.minute = read_rtc_time_register(REG_RTC_MINUTES);
+        t.second = read_rtc_time_register(REG_RTC_SECONDS);
+        /* Hour field is treated differently because it might have 'PM' flag
+         * in highest bit if we're in 24-hour mode. */
+        ubyte hour = read_register(REG_RTC_HOURS);
+        ubyte pm = hour >> 7u;
+        hour &= 0x7Fu;
+        if (!rtc_binary_mode)
+        {
+            /* Hour is in BCD format; convert to binary. */
+            hour = bcd_to_binary(hour);
+        }
+        if (!rtc_24hour_mode)
+        {
+            /* Hour is in 12-hour format; convert to 24-hour format. */
+            hour = cast(ubyte)((hour % 12u) + pm * 12u);
+        }
+        t.hour = hour;
+        return t;
+    }
+
+    private static ubyte read_rtc_time_register(ubyte register)
+    {
+        ubyte value = read_register(register);
+        if (!rtc_binary_mode)
+        {
+            value = bcd_to_binary(value);
+        }
+        return value;
+    }
+
+    private static ubyte bcd_to_binary(ubyte bcd)
+    {
+        return (bcd & 0xFu) + ((bcd & 0xF0u) >> 4u) * 10u;
+    }
+}

src/hulk/serial.d

@@ -0,0 +1,74 @@
+/**
+ * Serial port access.
+ */
+module hulk.serial;
+
+import hulk.cpu;
+import core.stdc.stdarg;
+static import hulk.writef;
+
+struct Serial
+{
+    enum BASE_PORT = 0x3F8;
+
+    /**
+     * Initialize the serial module.
+     */
+    static void initialize()
+    {
+    }
+
+    /**
+     * Write a character to the serial port.
+     *
+     * @param ch Character to write.
+     */
+    static void write(ubyte ch)
+    {
+        if (ch == '\n')
+        {
+            out8(BASE_PORT, '\r');
+        }
+        out8(BASE_PORT, ch);
+    }
+
+    /**
+     * Write a formatted string to the serial port.
+     *
+     * @param s Format string.
+     * @param args Variable arguments structure.
+     */
+    public static void writef(string s, va_list args)
+    {
+        hulk.writef.writef(s, args, function void(ubyte ch) {
+                    Serial.write(ch);
+                });
+    }
+
+    /**
+     * Write a formatted string to the serial port.
+     *
+     * @param s Format string.
+     */
+    public static extern (C) void writef(string s, ...)
+    {
+        va_list args;
+        va_start(args, s);
+        writef(s, args);
+        va_end(args);
+    }
+
+    /**
+     * Write a formatted string and newline to the serial port.
+     *
+     * @param s Format string.
+     */
+    public static extern (C) void writefln(string s, ...)
+    {
+        va_list args;
+        va_start(args, s);
+        writef(s, args);
+        writef("\n", args);
+        va_end(args);
+    }
+}

src/hulk/usb/xhci.d

@@ -0,0 +1,104 @@
+/**
+ * eXtensible Host Controller Interface for Universal Serial Bus
+ *
+ * Documentation:
+ * - https://wiki.osdev.org/EXtensible_Host_Controller_Interface
+ * - https://www.intel.com/content/dam/www/public/us/en/documents/technical-specifications/extensible-host-controler-interface-usb-xhci.pdf
+ */
+
+module hulk.usb.xhci;
+
+import hulk.pci;
+import hulk.hurl.a1;
+import hulk.klog;
+
+struct XHCI
+{
+    /**
+     * Located at PCI base address.
+     */
+    struct CapabilityRegisters
+    {
+        ubyte capability_length;
+        ubyte _reserved01;
+        ushort hci_version;
+        uint[3] hcs_params;
+        uint hcc_params1;
+        uint doorbell_offset;
+        uint rts_offset;
+        uint hcc_params2;
+    }
+    static assert(CapabilityRegisters.sizeof == 0x20u);
+
+    /**
+     * Located at offset capability_length from PCI base address.
+     */
+    struct OperationalRegisters
+    {
+        uint usb_command;
+        uint usb_status;
+        uint page_size;
+        uint[2] _reserved01;
+        uint dn_ctrl;
+        ulong cr_ctrl;
+        uint[4] _reserved02;
+        ulong dcbaap;
+        uint config;
+        uint _reserved03;
+    }
+    static assert(OperationalRegisters.sizeof == 0x40u);
+
+    /**
+     * Located at offset 0x400 from start of Operational Registers.
+     */
+    struct PortRegisters
+    {
+        uint portsc;
+        uint portpmsc;
+        uint portli;
+        uint porthlpmc;
+    }
+    static assert(PortRegisters.sizeof == 0x10u);
+
+    struct RuntimeRegisters
+    {
+        uint mfindex;
+        uint[7] _reserved01;
+        uint ir;
+    }
+
+    struct DoorbellRegister
+    {
+        ubyte target;
+        ubyte _reserved01;
+        ushort task_id;
+    }
+    static assert(DoorbellRegister.sizeof == 4u);
+
+    private CapabilityRegisters * m_capability_registers;
+    private OperationalRegisters * m_operational_registers;
+    private PortRegisters * m_port_registers;
+    private RuntimeRegisters * m_runtime_registers;
+    private DoorbellRegister * m_doorbell_registers;
+
+    void initialize(Pci.Device * pci_device)
+    {
+        void * base_address = pci_device.memory_ranges[0].address;
+        Klog.writefln("Found XHCI controller at address %x", base_address);
+        m_capability_registers = cast(CapabilityRegisters *)base_address;
+        m_operational_registers = cast(OperationalRegisters *)(base_address + m_capability_registers.capability_length);
+        /* TODO: confirm if 0x400 offset is from m_operation_registers or base_address. */
+        m_port_registers = cast(PortRegisters *)(cast(void *)m_operational_registers + 0x400);
+        m_runtime_registers = cast(RuntimeRegisters *)(base_address + m_capability_registers.rts_offset);
+        m_doorbell_registers = cast(DoorbellRegister *)(base_address + m_capability_registers.doorbell_offset);
+    }
+
+    static void build(Pci.Device * pci_device)
+    {
+        if (pci_device.memory_ranges[0].address != null)
+        {
+            XHCI * xhci = A1.allocate!XHCI();
+            xhci.initialize(pci_device);
+        }
+    }
+}

src/hulk/util.d

@@ -0,0 +1,17 @@
+/**
+ * HULK utility functions.
+ */
+module hulk.util;
+
+/**
+ * Round a value up to the next power of 2.
+ *
+ * @param v Value to round up.
+ * @param p Power of 2 to round up to.
+ *
+ * @return Rounded up value.
+ */
+ulong round_up_power_2(ulong v, ulong p)
+{
+    return (v + p - 1u) & ~(p - 1u);
+}

src/hulk/writef.d

@@ -26,7 +26,15 @@ size_t writef(string s, va_list args, ch_out_fn ch_out)
     {
         if (escape)
         {
-            if (c == 'x')
+            if (c == 'c')
+            {
+                ulong ch;
+                va_arg(args, ch);
+                ch_out(cast(ubyte)ch);
+                length_written++;
+                escape = false;
+            }
+            else if (c == 'x')
             {
                 ulong v;
                 va_arg(args, v);

x86_64-elf-gcc.rb

@@ -21,23 +21,30 @@ end
 
 default do
   unless Dir.exist?(install_path)
+    puts "Building cross compiler toolchain..."
+
     # Download archives.
+    puts "Downloading binutils..."
     download "https://ftp.gnu.org/gnu/binutils/binutils-#{binutils_version}.tar.xz",
       "#{build_dir}/binutils-#{binutils_version}.tar.xz",
       sha256sum: binutils_checksum
 
+    puts "Downloading gcc..."
     download "https://ftp.gnu.org/gnu/gcc/gcc-#{gcc_version}/gcc-#{gcc_version}.tar.xz",
       "#{build_dir}/gcc-#{gcc_version}.tar.xz",
       sha256sum: gcc_checksum
 
     # Extract archives.
+    puts "Extracting binutils..."
     sh "tar", "xJf", "binutils-#{binutils_version}.tar.xz",
       chdir: build_dir
 
+    puts "Extracting gcc..."
     sh "tar", "xJf", "gcc-#{gcc_version}.tar.xz",
       chdir: build_dir
 
     # Build binutils.
+    puts "Building binutils..."
     rm_rf "#{build_dir}/build-binutils"
     mkdir_p "#{build_dir}/build-binutils"
     cd "#{build_dir}/build-binutils" do
@@ -49,6 +56,7 @@ default do
     end
 
     # Build gcc.
+    puts "Building gcc..."
     rm_rf "#{build_dir}/build-gcc"
     mkdir_p "#{build_dir}/build-gcc"
     cd "#{build_dir}/build-gcc" do
@@ -62,6 +70,7 @@ default do
     end
 
     # Remove archives and build directories if everything succeeded.
+    puts "Cleaning up..."
     rm_f "#{build_dir}/binutils-#{binutils_version}.tar.xz"
     rm_rf "#{build_dir}/binutils-#{binutils_version}"
     rm_rf "#{build_dir}/build-binutils"